a piece of transparent substance, usually glass, having two opposite surfaces either both curved or one curved and one plane, used in an optical device in changing the convergence of light rays, as for magnification, or in correcting defects of vision.
a combination of such pieces.
some analogous device, as for affecting sound waves, electromagnetic radiation, or streams of electrons.
1690s, "glass to regulate light rays," from Latin lens (genitive lentis) "lentil," on analogy of the double-convex shape. See lentil. Of the eye from 1719.
In the vernacular of the photographer, anyone crowding to the front of a group, staring into the lens, or otherwise attracting attention to himself is known as a "lens louse." ["American Photography," vol. 40, 1946; the term dates from 1915]
A ground or molded piece of glass, plastic, or other transparent material with opposite surfaces either or both of which are curved, by means of which light rays are refracted so that they converge or diverge to form an image.
A transparent, biconvex body of the eye between the iris and the vitreous humor that focuses light rays entering through the pupil to form an image on the retina.
A transparent structure behind the iris of the eye that focuses light entering the eye on the retina.
A piece of glass or plastic shaped so as to focus or spread light rays that pass through it, often for the purpose of forming an image.
A combination of two or more such lenses, as in a camera or telescope. Also called compound lens
A device that causes radiation to converge or diverge by an action analogous to that of an optical lens. The system of electric fields used to focus electron beams in electron microscopes is an example of a lens.